The present invention relates generally to chewing gums. More specifically, the present invention relates to chewing gums that can provide dental benefits.
Except for the common cold, dental caries (tooth decay) is the most prevalent human disorder. See, The Merck Manual, Sixteenth Edition, p. 2480. Even though, many steps have been taken to reduce dental caries and tooth decay, such as fluoridation and improved dental care, tooth decay continues to be a significant problem, this is especially true in the adult population; 80% of the tooth decay occurs in 20% of the population. See, Featherstone, An Updated Understanding of the Mechanism of Dental Decay and its Prevention, Nutrition Quarterly, Vol. 14, No. 1, 1990, pp. 5-11.
To protect a normal tooth, a thin layer of dental enamel forms a protective coating over the tooth. This coating consists mainly of calcium, phosphate, and other ions in a hydroxyapatite-like structure. The enamel contains 2-5 percent carbonate; this carbonate content makes the enamel susceptible to acid dissolution. See, Featherstone, id. at 6.
The interaction of three factors is believed to result in dental caries: a susceptible tooth surface; the proper microflora; and suitable substrate for the microflora. Although several acidogenic micro-organisms that are present in the mouth can initiate carious lesions, Streptococcus mutans is believed to be the primary pathogen. See, The Merck Manual, supra.
It is know that foods containing fermentable carbohydrates can promote dental caries. Tooth decay begins when the Streptococcus mutans, that reside principally in the plaque that adheres to a tooth surface, metabolize the fermentable carbohydrates consumed by the host. During the metabolism of the fermentable carbohydrates by the bacteria, lactic acid and other organic acids are secreted as a by-product. These acids reduce the pH of the surrounding plaque/tooth environment.
When the pH of the plaque/tooth environment drops below a critical level of 5.5 to 5.7, hydroxyapatite (calcium phosphate hydroxide, Ca.sub.10 (PO.sub.4).sub.6 (OH).sub.2), the key component of tooth enamel, begins to dissolve. Typically, the dissolution begins below the tooth's porous surface.
With repeated acid attacks, caused by the further metabolism of fermentable carbohydrates by the bacteria, subsurface lesions expand. The body's natural remineralization mechanism, however, at this point, can still reverse the decay process. But, if the lesions expand to the point that the enamel surface breaks, a cavity is formed and the process is no longer reversible.
The natural remineralization process involves, in part, the flow of saliva over the plaque. The saliva can raise the pH of the environment. Additionally, calcium and phosphate ions in the saliva precipitate out to replace the hydroxyapatite that was dissolved by the organic acids created during the metabolism of the fermentable carbohydrates.
However, typically, this remineralization process only occurs at significant levels when the pH is above the critical level. Therefore, if the saliva does not sufficiently raise the pH, significant remineralization will not occur. But, the remineralization process may be enhanced by fluoride in the oral cavity that speeds up new crystal growth and makes a fluorapatite-like material that is precipitated on the surface of the crystals inside the carie lesion. See, Featherstone, id. at 7.
Although a number of salts have been reported in certain experiments to counteract the decay process, no acceptable method of treatment using such salts, in the opinion of the inventor of the present invention, has been provided. One of the difficulties is providing a viable vehicle for delivering the salts. Still further, a number of safety issues are raised by some of the salts. Furthermore, sensory problems with respect to some of the salts prevent these salts from being taken on a regular basis by a patient to provide prophylactic benefits.